TheHydrobia ulvae–Maritrema subdolumassociation: cercarial emergence controlled by host activity

2002 ◽  
Vol 76 (4) ◽  
pp. 349-353 ◽  
Author(s):  
K.N. Mouritsen
Keyword(s):  
Experimental Data ◽  
Adaptive Significance ◽  
Published Data ◽  
Hydrobia Ulvae ◽  
Mud Snail ◽  
Emergence Rate ◽  
Presence And Absence ◽  
Marine Mud ◽  
Cercarial Emergence

AbstractThe release ofMaritrema subdolumcercariae (Digenea: Microphallidae) from the marine mud snailHydrobia ulvaeis significantly affected by temperature, salinity, light and exudates from the second intermediate amphipod host. Based on (i) previously published data on temperature–salinity dependentH. ulvaeactivity, (ii) new experimental data onH. ulvaeactivity in light and darkness as well as in the presence and absence of host exudates, and (iii) the cercarial emergence rate from free moving snails and snails prevented from crawling, the present analysis indicates that emergence ofM. subdolumlarvae is regulated mainly by host activity as the ultimate factor for release. The adaptive significance of such an emergence strategy is emphasized.

scholarly journals The Hydrobia ulvae–Maritrema subdolum association: influence of temperature, salinity, light, water-pressure and secondary host exudates on cercarial emergence and longevity

2002 ◽  
Vol 76 (4) ◽  
pp. 341-347 ◽  
Author(s):  
K.N. Mouritsen
Keyword(s):  
Intermediate Host ◽  
Water Pressure ◽  
Fold Increase ◽  
Corophium Volutator ◽  
Transmission Strategy ◽  
Hydrobia Ulvae ◽  
Emergence Rate ◽  
Second Intermediate Host ◽  
The Impact ◽  
Cercarial Emergence

AbstractThe effects of environmental factors and exudates from the amphipod Corophium volutator on the emergence of Maritrema subdolum cercariae (Digenea: Microphallidae) from the snail Hydrobia ulvae were investigated in the laboratory. Increasing the temperature (15 to 25°C) caused an overall 11-fold increase in emergence rate under varying salinities (24 to 36‰). The effect of salinity depended on the experimental temperature. Emergence increased with increasing salinity at higher temperatures, but decreased with increasing salinity at 15°C.Whereas the different levels of salinity had no effect, increasing the temperature significantly reduced the life span of cercariae. In comparison with complete darkness, light caused a two-fold increase in emergence, whereas an increment of the water pressure from 1.0 to 1.3 ATM (corresponding to 0 and 3 m of depth) left the shedding rate unaffected. Unidentified exudates from the second intermediate host, C. volutator, significantly depressed the cercarial emergence rate. The main transmission window of M. subdolum seems to occur during low water in tidal pools where light levels are high and solar radiation rapidly elevates the water temperature, as well as salinity through evaporation. The consequence of such a transmission strategy is discussed in relation to the impact of M. subdolum on the population dynamics of the second intermediate host.

Predation of the shelduck Tadorna tadorna on the mud snail Hydrobia ulvae

2008 ◽  
Vol 43 (4) ◽  
pp. 1193-1199 ◽  
Author(s):  
N. R. Anders ◽  
T. Churchyard ◽  
J. G. Hiddink
Keyword(s):  
Hydrobia Ulvae ◽  
Mud Snail

Application of Polyhedral Mesh for Vortex Formation Study for Simple Single Pump Sump

CFD letters ◽  
2021 ◽  
Vol 13 (9) ◽  
pp. 13-27
Author(s):  
Mohamad Lutfi Samsudin ◽  
Hasril Hasini
Keyword(s):  
Experimental Data ◽  
Complex Geometry ◽  
Vortex Formation ◽  
Tetrahedral Mesh ◽  
Published Data ◽  
Hexahedral Mesh ◽  
The Past ◽  
Polyhedral Mesh ◽  
Pump Sump ◽  
Comparison Of The Results

Meshing of domain in CFD is an important step to ensure accuracy of the solution. In the past, hexahedral or tetrahedral mesh systems were commonly used, and both have their merits and demerits. For large and complex geometry, polyhedral is another option but its accuracy is claimed to be lacking. In this paper, the use of polyhedral mesh system by past researchers are reviewed. Evaluation on the application of polyhedral mesh system for the study of the vortex formation with a simple single pump sump model is made. Validation was made through the comparison of the results from hexahedral, tetrahedral and polyhedral mesh sizes and the experimental data from published data. The polyhedral mesh system was found to perform satisfactorily and was able to match the results from the hexahedral mesh system as well as the experimental data.

High-enthalpy, water-cooled and thin-walled ICP sources characterization and MHD optimization

2008 ◽  
Vol 74 (3) ◽  
pp. 391-429 ◽  
Author(s):  
G. HERDRICH ◽  
D. PETKOW
Keyword(s):  
Experimental Data ◽  
Magnetic Pressure ◽  
Maximum Pressure ◽  
Published Data ◽  
Space Vehicles ◽  
Maximum Plasma ◽  
Plasma Power ◽  
New Model ◽  
High Enthalpy ◽  
Lorentz Forces

AbstractThe development of the inductively driven plasma wind tunnel PWK3, which enables the electrodeless generation of high-enthalpy plasmas for the development of heat shield materials required for space vehicles performing entry manoeuvres in the atmospheres of Venus, Earth and Mars, is described. The facility with its modular inductive plasma generators allows operation with gases such as carbon dioxide, air, oxygen and nitrogen and was qualified for thermal plasma powers up to 60 kW. Previously developed models for determining plasma properties and plasma source related characteristics enable a maximum plasma power in combination with long operational periods using different operational gases and gas mixtures. This is achieved by an optimization using the optimum operational frequency, a minimization of field losses using very thin plasma tube wall thicknesses and the successful application of MHD effects. Based on the solved cylinder problem for ICPs, a one-dimensional model for radial Lorentz forces and magnetic pressure has been developed. Here, a synthesis of previously published data and works is made where the new algebraic model for the calculation of Lorentz forces and magnetic pressures in an ICP was used and applied to experimental data. In addition, results from the model using the experimental data are shown to be consistent and, in addition, a comparison with a simpler model based on the well-known exponential approach for ICPs showed that the simpler model is covered without fail by the new model. The new model also states that there is a maximum of the Lorentz forces over the damping parameter d/δ (plasma diameter divided by skin depth) which almost corresponds with the position of the maximum plasma power of the cylindric model for ICPs. For the magnetic pressure the position of the maximum pressure is identical to the value for d/δ for the maximum plasma power.

Measurement of ingestion rate of Hydrobia ulvae (Pennant) on intertidal epipelic microalgae: the effect of mud snail density

2000 ◽  
Vol 255 (2) ◽  
pp. 247-260 ◽  
Author(s):  
Gérard F Blanchard ◽  
Jean-Marc Guarini ◽  
Laurent Provot ◽  
Pierre Richard ◽  
Pierre-Guy Sauriau
Keyword(s):  
Ingestion Rate ◽  
Snail Density ◽  
Hydrobia Ulvae ◽  
Mud Snail

scholarly journals Optimization of Interfacial Energy for Langer-Schwartz Based Precipitation Simulations

2021 ◽  
Author(s):  
Conner Sarich ◽  
Adam Hope ◽  
Jim Rule
Keyword(s):  
Experimental Data ◽  
Interfacial Energy ◽  
Volume Fraction ◽  
Published Data ◽  
Low Alloy Steels ◽  
Interfacial Energies ◽  
Nucleation Sites ◽  
Alloy Steels ◽  
Thermal Histories ◽  
Al 2024

Abstract Precipitation kinetics were investigated in select Fe, Ni, and Al alloys using a CALPHAD based precipitation model based on Langer-Schwartz theory. Thermodynamic and kinetic data are taken from commercially available CALPHAD software, but reliable interfacial energy data for precipitates needed for the calculations is often lacking. While models exist to approximate these interfacial energies, this study has focused on deriving more reliable estimates by comparison with experimental data. By performing simulations with thermal histories, nucleation sites, and precipitate morphologies that closely replicate experimental data found in literature, the interfacial energies were optimized until volume fraction and mean radius values closely matched the published data. Using this technique, interfacial energy values have been determined for carbides in Grade 22 low alloy steels, delta phase in Ni 625 and 718, SPhase in Al 2024, and Q’ and β’’ in Al 6111, and can be used for future predictive precipitation simulations.

scholarly journals Carbides and Nitrides of Zirconium and Hafnium

Materials ◽  
2019 ◽  
Vol 12 (17) ◽  
pp. 2728 ◽  
Author(s):  
Sergey V. Ushakov ◽  
Alexandra Navrotsky ◽  
Qi-Jun Hong ◽  
Axel van de Walle
Keyword(s):  
Experimental Data ◽  
Phase Equilibria ◽  
Ab Initio ◽  
Solid Solutions ◽  
Binary Systems ◽  
Experimental Studies ◽  
Published Data ◽  
Oxygen Solubility ◽  
Melting Temperatures ◽  
Ab Initio Computations

Among transition metal carbides and nitrides, zirconium, and hafnium compounds are the most stable and have the highest melting temperatures. Here we review published data on phases and phase equilibria in Hf-Zr-C-N-O system, from experiment and ab initio computations with focus on rocksalt Zr and Hf carbides and nitrides, their solid solutions and oxygen solubility limits. The systematic experimental studies on phase equilibria and thermodynamics were performed mainly 40–60 years ago, mostly for binary systems of Zr and Hf with C and N. Since then, synthesis of several oxynitrides was reported in the fluorite-derivative type of structures, of orthorhombic and cubic higher nitrides Zr3N4 and Hf3N4. An ever-increasing stream of data is provided by ab initio computations, and one of the testable predictions is that the rocksalt HfC0.75N0.22 phase would have the highest known melting temperature. Experimental data on melting temperatures of hafnium carbonitrides are absent, but minimum in heat capacity and maximum in hardness were reported for Hf(C,N) solid solutions. New methods, such as electrical pulse heating and laser melting, can fill the gaps in experimental data and validate ab initio predictions.

Interpretation of Mechanical Testing Measurements for Pastes

2002 ◽  
Author(s):  
Robert A. Basterfield ◽  
Chris J. Lawrence ◽  
Michael J. Adams
Keyword(s):  
Experimental Data ◽  
Numerical Models ◽  
Experimental Methods ◽  
Published Data ◽  
The Finite Element Method ◽  
Material Parameters ◽  
Simulation Techniques ◽  
Manufacturing Sectors ◽  
Product Forms ◽  
Computer Simulation Techniques

Pastes occur as intermediates or final product forms in many industrially important manufacturing sectors. The use of computer simulation techniques, such as the finite element method, is becoming more common in the design of paste processing operations. A major problem in the application of this approach is the development of sufficiently representative materials models. It has been established that pastes may be described as elasto-viscoplastic materials with the plastic flow being governed by the Herschel-Bulkley relationship. This paper describes the development of analytical and numerical models that can be used as a basis for deriving the material parameters from experimental data obtained using extrusion, compression and bending procedures. Measurements have also been carried out on a model paste and the derived material parameters are compared with published data for the same paste. The merits of the three experimental methods are compared on this basis.

Prediction of Ingestion Through Turbine Rim Seals—Part II: Externally Induced and Combined Ingress

2010 ◽  
Vol 133 (3) ◽  
Author(s):  
J. Michael Owen
Keyword(s):  
Experimental Data ◽  
Flow Rate ◽  
Gas Turbines ◽  
Swirling Flows ◽  
Published Data ◽  
Flow Rates ◽  
Hot Gas ◽  
Predicted Values ◽  
Good Agreement

Ingress of hot gas through the rim seals of gas turbines can be modeled theoretically using the so-called orifice equations. In Part I of this two-part paper, the orifice equations were derived for compressible and incompressible swirling flows, and the incompressible equations were solved for axisymmetric rotationally induced (RI) ingress. In Part II, the incompressible equations are solved for nonaxisymmetric externally induced (EI) ingress and for combined EI and RI ingress. The solutions show how the nondimensional ingress and egress flow rates vary with Θ0, the ratio of the flow rate of sealing air to the flow rate necessary to prevent ingress. For EI ingress, a “saw-tooth model” is used for the circumferential variation of pressure in the external annulus, and it is shown that ε, the sealing effectiveness, depends principally on Θ0; the theoretical variation of ε with Θ0 is similar to that found in Part I for RI ingress. For combined ingress, the solution of the orifice equations shows the transition from RI to EI ingress as the amplitude of the circumferential variation of pressure increases. The predicted values of ε for EI ingress are in good agreement with the available experimental data, but there are insufficient published data to validate the theory for combined ingress.

Prediction of Ingestion Through Turbine Rim Seals—Part 2: Externally-Induced and Combined Ingress

2009 ◽  
Author(s):  
J. Michael Owen
Keyword(s):  
Experimental Data ◽  
Flow Rate ◽  
Gas Turbines ◽  
Swirling Flow ◽  
Published Data ◽  
Flow Rates ◽  
Hot Gas ◽  
Predicted Values ◽  
Good Agreement

Ingress of hot gas through the rim seals of gas turbines can be modelled theoretically using the so-called orifice equations. In Part 1 (ASME GT 2009-59121) of this two-part paper, the orifice equations were derived for compressible and incompressible swirling flow, and the incompressible equations were solved for axisymmetric rotationally-induced (RI) ingress. In Part 2, the incompressible equations are solved for non-axisymmetric externally-induced (EI) ingress and for combined EI and RI ingress. The solutions show how the nondimensional ingress and egress flow rates vary with Θ0, the ratio of the flow rate of sealing air to the flow rate necessary to prevent ingress. For EI ingress, a ‘saw-tooth model’ is used for the circumferential variation of pressure in the external annulus, and it is shown that ε, the sealing effectiveness, depends principally on Θ0; the theoretical variation of ε with Θ0 is similar to that found in Part 1 for RI ingress. For combined ingress, the solution of the orifice equations shows the transition from RI to EI ingress as the amplitude of the circumferential variation of pressure increases. The predicted values of ε for EI ingress are in good agreement with available experimental data, but there are insufficient published data to validate the theory for combined ingress.

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